Poly propylene (PP) is one of the famous polymers with great application. In this study, CFD model on dynamics of the fluidized bed polyethylene production process has been investigated. A detailed CFD model for sticky poly propylene fluidized bed was formulated in this work. As a result, detailed information on the PSD and hydrodynamic fields of the gas and solid phases can be obtained from the simulations. Defluidization due to particle aggregation also can be simulated. For modeling plant–scale poly propylene reactors, a chemical look–up table should be used to solve efficiently the solid species equations.. In order to address all the issues in FB polymerization, models for simplified polymerization kinetics, polydisperse multiphase flow, and mass and heat transfer between the gas and solid particles are combined together. As a result, physically aggregation because of atactic polypropylene is more important than other aggregation reasons. Finally, as mentioned earlier, after DQMOM is applied to the multi–fluid CFD model, new terms accounting for the effect of aggregation and breakage need to be added on the right–hand sides of the solid–phase momentum, energy, and species equations. These modifications and detailed simulation results for plant–scale fluidized bed polymerization reactors will be reported in future communications

Gas–solid fluidized bed reactors have many industrial applications and have been studied by many researchers. In this study, the 2D hydrodynamics of fluidized bed was investigated by using CFD analysis. To perform the simulation of fluidized bed, the...

In diffusion combustion systems, turbulent mixing of the oxidant (usually air) with fuel is affected by the burner design. Enhanced mixing process can help to tailor the performance of the flame and pollutant emission characteristics of the furnace....

Sedimentation of adsorbent particles was investigated for obtaining the sedimentation properties of the adsorbent. The suspension was modeled assuming three regions including clear liquid, variablecomposition and sediment zone exist in the column. A semi–empirical correlation was derived foradsorbent particles concentration distribution as a function of time and overall suspension depth. Mass transfer into adsorbent was modeled using proposed concentration distribution function of adsorbents. Colloid concentration distribution in suspended liquid was calculated with time and liquid depth numerically. An effect of sedimentation properties on adsorption efficiency was investigated

Submerged vanes are small hydraulic structures to conduct flow and sediment in river bed, which may be installed in single or group patterns. Submerged vanes are, about two decades, used to control rive intake sedimentation and river bank protection....

A new radiation met hod is proposed for modeling the radiative heat transfer within combustion chambers. This method can obtain temperature profiles and heat transfer in an emitting, absorbing and scattering media of non–uniform absorptivity. In this...

Underground hydropower projects consist of complex underground spaces. Usually the powerhouse caverns are the largest and the most complex part of these spaces.The excavation and supporting sequences of these caverns are crucial from technical,...

A bonded particle model is used in three point bending simulation of rock fracture to investigate whether size of fracture process zone is an intrinsic material property. Different sample sizes are used. The normal bond between particles at contact...

Sedimentation is one of the most important problems in harbors that results in considerable economic costs. Harbor planforms affects the flow pattern in the harbor basin and consequently, plays an important role in sediment transport and...

The structure of porous media in format of electron microscopy image was used and geometry of fluid flow in a sample porous media was created. The flowpatterns are described and the pressure and the shear stress at the fluid\solid surfaces are analyzed in the porous media by means of Computational Fluid Dynamic. Threelaminar flow regimes; Darcy, transition and strong inertia were shown. As a consequence, the Non–Darcy 2D–flow is correctly modelled by Forchheimer’sequation. Capillary pressure hysterics in drainage and imbibitions of wetting phase to porous media because of pore structure has been shown. Residual saturation of nonwetting and wetting phases in drainage and imbibitions has been illustrated, too.Finally, connection between imaging results and informative data bank from numerical modelling was shown

This paper is concerned to modeling an industrial High Temperature water Gas shift Fixed bed reactor. The gas flow through packed beds is treated as flow through a porous medium. The resistance flow due to the presence of the porous medium is...

In this research method of CFD is used to simulate hydrodynamic and mass transfer in airlift reactors. The main purpose is to investigate effect of changing in bubble size on hydrodynamic and mass transfer characteristics. The most important...

Plate fin and tube heat exchangers have many applications in air conditioning and radiators of internal combustion motors. The geometrical parameters have had considerable effects on heat transfer and pressure drop of these heat exchangers....

Sedimentation of adsorbent particles was investigated for obtaining the sedimentation properties of the adsorbent. The suspension was modeled assuming three regions including clear liquid, variable composition and sediment zone exist in the column. A semi–empirical correlation was derived for adsorbent particles concentration distribution as a function of time and overall suspension depth. Mass transfer into adsorbent was modeled using proposed concentration distribution function of adsorbents. Colloid concentration distribution in suspended liquid was calculated with time and liquid depth numerically. An effect of sedimentation properties on adsorption efficiency was investigated.

The applicability and usefulness of porous burners are of high interest due to their competitive combustion efficiency, high power dynamic range, compactness and lower pollutants formation. In this research two–dimensional numerical predictions of...

Three different numerical methods such as orthogonal collocation, finite difference and shooting method are performed comparatively for modeling a straight membrane gas reactor and the results have been compared by analytical solution. The...

Seepage and stability analyses of two cross–sections of concrete face rock–fill dams,homogeneous and zoned embankments, are investigated in the present study due to cracking of the concrete slab. Seepage and stability analyses are investigated by...

The analysis of submergence in rockfill dams and road embankments is of great importance because of collapse settlement that occurs during first impounding. Here collapse settlement due to saturation of a rockfill media in a column and an embankment...

Sedimentation of adsorbent particles was investigated for obtaining the sedimentation properties of the adsorbent. The suspension was modeled assuming three regions including clear liquid, variablecomposition and sediment zone exist in the column. A...